Many beneficial drugs are administered at a definite time for their beneficial effects. For example, sleeping aids that help in falling asleep are usually taken before bed and then, if needed, at a later time, say four or five hours later. Then too, the symptomatic relief of anxiety and tension, and the relief from pain and inflammation, usually requires an initial pulse or first dose supplemented at a later interval by another pulse or second dose. The pulsatile delivery of drugs having a short half-life, that is drugs that lose one-half of their therapeutic activity because the drug is metabolized or excreted, require pulsed administration at recurring intervals. Also, it is often desirable to administer a drug in a form that makes the drug available at a later time for a pulsed delivery of the drug. The need for pulsed delivery arises during a circadian or chronological cycle, for drugs with a pronounced first post effect and for drugs which on continuous low level may lead to tolerance.
Prior to this invention, drugs with short half-lives were often administered to a recipient once-or-twice in separate dosage forms during a given time span, for example one-or-two doses to obtain the benefit of the drugs pharmacokinetic activity. This type of repeated dosing is accompanied with shortcomings. For example, when a drug is administered at bed time the presently available prior art dosage forms requires repeated dosing the recipient and interrupting the sleep for the next dose. Then too, a recipient on a therapeutic program often forgets to take the next dose, and this lack of compliance leads to a drug-free interval during which interval the recipient does not get the benefit of the next needed dose.
It is immediately apparent in the light of the above presentation that a pressing need exists for a dosage form that can delay the delivery of a drug and then deliver a pulsed dose of drug. It is apparent also that a pressing need exists for a dosage form that can immediately deliver a pulsed dose of drug followed by a drug-free interval and then deliver a pulsed dose of drug. It will be appreciated by those versed in the dispensing art, that if a novel and unique dosage form is made available for executing a therapeutic program comprising pulsed and delayed drug delivery patterns, such a dosage form would have a practical application and it would also represent a valuable contribution to the medical and veterinary arts.